code: def test_load_stage_mapping(dvc, stage_data, lock_data):
      dvcfile = load_file(dvc, PROJECT_FILE)
      dvcfile.contents = {"stages": {"stage": stage_data}}
      dvcfile.lockfile_contents = {"stage": lock_data}
  
      assert len(dvcfile.stages) == 1
      assert "stage" in dvcfile.stages
      assert "stage1" not in dvcfile.stages
      assert dvcfile.stages.keys() == {"stage"}
      assert isinstance(dvcfile.stages["stage"], PipelineStage)
  
imports: import os
  from copy import deepcopy
  from itertools import chain
  import pytest
  from dvc.dvcfile import PROJECT_FILE, load_file
  from dvc.stage import PipelineStage, create_stage
  from dvc.stage.loader import StageLoader
  from dvc.stage.serialize import split_params_deps
  from dvc_data.hashfile.hash_info import HashInfo
label_desc: Use image node_id 19 for calling a global function with example usage: test_load_stage_mapping(dvc, stage_data, lock_data) without return types